[28-29] What then, given the contemporary formulation of the general philosophical problem, are the possible alternatives? The alternative can be only one, for the whole matter comes down to preserving science and practical activity in the closest possible unity, without sacrificing one for the other, without opposing them to one another. This means either practical activity will be derived from science, or conversely, science will be derived from practical activity... In one case we obtain rationalistic, intellectualistic and positivistic systems — the dogmatism of science. In the other case we obtain systems of pragmatism, fideism, or active intuition (such as Bergson's) — the dogmatism of action. According to the first systems one must know in order to act: knowledge produces action. According to the second systems knowledge is guided by the needs of action: action produces knowledge.

But let the reader not think that these latter systems wish to resurrect contempt for science and a philosophy of ignorance. No, only after serious investigation, on the basis of scientific, often excellent erudition, deep critical reflections on science and even vigorous "mental absorption into science," as some of these philosophers like to say, do they arrive at deriving science from practice. If they thereby diminish science, they do so unintentionally; many of them think, on the contrary, to reveal in this way all its value...